The invention relates to apparatus for removing impurities, e.g. heavy components such as husks, leaves and stem particles from a fiber material flow, in particular from spinning material fibers, e.g. textile fiber flocks of cotton, etc. The fiber material flow is pneumatically conveyed past a deviation zone. Within the deviation zone, separation of heavy components is provided by openings in the form of a screen or grid etc. Upon its deviation, the fiber material air current is further conducted in a channel.
There have been known various embodiments of separating means for removing waste particles from a textile fiber material current. The waste particles which, for the major part, are heavier than the fiber material, are removed by air sifting. In a separation zone, generally disposed in a deviation portion of a channel for the fiber flow, there are arranged grids formed of separating blades disposed in mutually parallel relationship. The separating blades are mounted transversely to the flow direction of the fiber material. However, the separating action is substantially affected by such a grid design. Due to the centrifugal force, heavy particles of the impurities are generally urged through the separating blades into a collecting chamber situated behind the blades. The lighter waste particles and even the fibers, often accumulate at the grid blades which are transverse to the flow direction. The lighter particles tend to adhere to the front edge of the grid knives. There is little chance for the lighter particles to be automatically liberated from said grid knives. There is a risk that the separating grid will become clogged, if passage through the grid knives is constricted by an accumulation of the lighter fiber particles.
It is the object of the invention to substantially improve the reliable and safe separating effect of a grid at the deviation point for a fiber material flow.